Vibratory impact tool



J. w. MARX 2,893,692

VIBRATORY IMPACT Toor.

5 Sheets-Sheet 1 F IG.

NVENTOR. J.W. MARX HW f July 7, 1959 Filed Jan. 3. 1955 Utri Yi....l..

ATTORNEYS .1. W. MARX VIBRATORY IMPACT TooL July 7, 1959 Filed Jan. 3, 1955 JNVENTOR.

J.W. MARX BY HWI@ 'f www A TTORNEVS July 7, 1959 Filed Jan. 5. 1955 J. W. MARX VIBRATORY IMPACT TOOL sheets-sheer 3 IN V EN TOR. J.W. MARX United .States Patent VIBRATORY IMPACT TO0L John W. Marx, Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Application January 3, 1955, Serial No. 479,305

14 Claims. (Cl. Z55-4) This invention relates to an improved vibratory impact tool. In another aspect it relates to an improved system for supplying electrical energy to vibrating element.

Vibratory impact tools of various types are known in the art. Such tools can be employed to advantage for a variety of drilling operations and -for impact operations such as expanding rivets. The vibrating element commonly is formed of a material possessing magnetostrictive, piezoelectric or magnetic properties. The application of proper lluctuating magnetic or electrical fields to such elements results in longitudinal vibration thereof. While the amplitudes of such vibrations normally are small, the elements may be vibrated at relatively high frequencies so that the total impact force ydeveloped is large. It has been discovered, for example, that earth drilling tools employing magnetostrictive vibrating means are capable of boring through hard rock at considerably faster rates than conventional rotary drills.

lt appears that the cutting rate of a vibratory drill is determined ultimately by the impact velocity of the vibrating member on the surface being drilled. This impact velocity varies as the product of the vibrational amplitude displacement and the operating frequency. In order to obtain large vibrational amplitudes, the drill member normally is vibrated at its mechanical resonance frequency. However, if the vibrating member is maintained in continuous and intimate contact with a solid surface being drilled, a large portion of the vibrational energy is transmitted across or otherwise dissipated at the surface. Such a loss of energy tends to nullify the advantage gained by operating at the resonant frequency to obtain maximum vibrational amplitudes.

It has now been discovered that maximum vibrational amplitudes can be provided by periodically disengaging the drill from the surface being drilled. This permits the resonance amplitude of vibration to be restored. This disengagement can be accompanied by applying two different driving frequencies to the vibrating member. By applying two different frequencies, a resulting beat frequency is obtained of frequency equal to the difference between the two applied frequencies. If this difference is properly selected, an effective separation of the vibrating element and the surface being drilled can be accomplished for periods sufficiently long to permit the resonance frequency to build up vibrations to relatively large amplitudes before the drill is reapplied to the surface. This principle is applicable to vibrating elements possessing'magnetostrictive, piezoelectric or magnetic properties. The disengagement can also be effected by an electromechanical device actuated periodically.

Accordingly, it is an object of this invention to provide an improved vibratory impact tool energized by two electrical signals of different frequencies.

Another object is to provide apparatus to transform electrical energy into vibratory mechanical energy in an elcient manner.

Another object is to provide means to increase the arnplitude of vibration of a vibratory impact tool by period- 2,893,692 latented July 7, 1959 ically separating said tool from the surface being drilled.

A further object is to provide improved earth drilling apparatus employing a vibrating drill bit.

Other objects, advantages and features of the invention should become apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

Figure l is a schematic representation of an earth drilling tool incorporating one embodiment of the present invention;

Figure 2 is a detailed sectional view of the drill illustrated in Figure l;

Figure 3 is a schematic representation of a magnetostrictive drill incorporating features of this invention;

Figure 4 is a schematic view of a second embodiment of a magnetostrictive drill incorporating features of this invention;

Figure 5 is a sectional view of a solenoid operated vibratory tool incorporating features of this invention; and

Figure 6 is a sectional View of a piezoelectric vibratory tool incorporating features of this invention.

Figure 7 is a sectional view of a vibratory tool, with a magnetostrictive resonating member, coupled with a solenoid to which a low frequency current is applied.

Referring now to the drawing in detail and to Figure l in particular, there is shown a drill assembly 10 suspended in a bore hole 15 by means of a cable 11 which extends over a pulley 12 to a drum 13. A flexible conduit 14 extends from the outlet of a pump 16 through the bore hole to assembly 10 to supply a suitable drilling fluid to remove cuttings from the hole. Electrical energy is supplied to the drill assembly by means of a flexible cable 17 which extends through the bore hole. The upper end of cable 17 is connected to a pair of alternating current generators 18 and 19 in a manner to be described in detail hereinafter.

Drill 10 is illustrated in detail in Figure 2. The assembly comprises an annular housing 20 which is threaded at its upper end to a coupling device 21. Coupling device 21 is secured to the lower ends of cable 11 and conduit 14 by suitable means, not shown. Drilling fluid is supplied to the interior of housing 20. An annular plug 22 is threaded to the lower end of housing 20 to support a pair of solenoids 23 and 24 within housing 20. An elongated sleeve 26 is positioned within housing 20 and is secured rigidly to housing 20 by a plurality of bars 27. Bars 27 engage sleeve 26 at approximately the midpoint thereof. Sleeve 26 is formed of a material, such as nickel or a nickel alloy, having magnetostrictive properties. Thus, the application of an alternating current to solenoids 23 and 24 results in sleeve 26 expanding and contracting at the frequency of the current applied to the solenoids. A coupling member 28 is threaded to the lower end of sleeve 26 to support a drill bit 30. Drill bit 30 is provided with one or more passages 31 therethrough to allow the drilling fluid to be circulated outwardly into the bore hole from the interior of the drill assembly. Member 26 need not be in the form of a hollow sleeve. In some applications a laminated bar can be used to advantage, for example.

Figure 3 is a schematic representation of the drilling apparatus of Figure 2 including the electrical components. Corresponding first end terminals of solenoids 23 and 24 are connected by respective conductors 33 and 34 to first end terminals of respective ammeters 35 and 36 which are positioned at the surface of the earth. Second end terminals of ammeters 35 and 36 are connected'to respective lirst output terminals of alternating current generators 18 and 19. The second output terminals of generators 18 and 19 are conveniently grounded, asare the second Yend terminals of solenoids 23 and 24. This grounding can be provided by cable 17 or by a connection to the metal housing of the drill assembly which is grounded by cable 11.

In order to obtain vibrations of maximum amplitude, electrical energy is supplied' to the coils surrounding magnetostrictive sleeve 26 at` approximately half the fundamental mechanical resonant frequency thereof. Since magnetostrictive changes in bar length are independent of the direction of the magnetic field, a mechanical vibration of frequency twice that of the alternating current applied to the coil winding'is produced. The fundamental resonant frequency for longitudinal vibrations of a lbar anchored at its midpoint is defined by the following equation:

i) fria where v is the velocity of sound in the bar, l is the length of the bar, and f is the fundamental mechanical resonant frequency. As a specific example, it is assumed that sleeve 26 is twenty-five feetV long and is constructed of a nicltel alloy which transmits sound at a velocity of 15,000 feet per second. When these values are substitutedin the above equation, it is found that the fundamental resonant frequency of vibration is 300 cycles per second. In order to obtain a beat frequency of four cycles per second, for example, generator 18 is adjusted to supply current at a frequency of 149 cycles per second and generator 19 is adjusted to supply current at l5l cycles per second. AIt is to be remembered that one cycle of applied current produces two' mechanical vibrations.

Of course, the attachment of drill bit 30 to the lower end of sleeve 26 changes the natural resonant frequency of the sleeve to a lower value fwhich may be of the order of`285 cycles per second in the above example. This new value can readily be determined by applying current from generator 18 only and adjusting the frequency of generator 18 while observing the current flow through ammeter 35. The current flow through ammeter 35 drops rapidly to a minimum when the drill assembly is vibrating at its resonant frequency. Once the natural resonant frequency of the assembly is determined, the frequencies of the two generators can be adjusted to supply the desired beat frequency.

In Figure 4 there is shown a schematic circuit diagram of'a second energizing system for the drilling assembly. Sleeve 26 is enclosed by a single solenoid 23' which is connected to ground at one end terminal. The second end terminal of solenoid 23 is connected to the center tap of an inductance coil 40, which preferably is positioned at the surface of the well. The end terminals of inductance coil 40 are connected to respective ammeters 35 and 36. Generators 18 and 19 are adjusted to supply the desired frequencies to produce a beat frequency in the manner described above in connection with Figure3. In the arrangement of Figure 4 it is important that the amplitudes of the currents supplied by generators 18 and 19 be maintained approximately equal to prevent interaction between the two generators. If this condition is fulfilled, the current flows from generators 18 and 19 are through the respective halves of inductance coil 40 and through solenoid 23'. A beat frequency results which is numerically equal to the difference between the two frequencies of generators 18 and 19.

In Figure there is shown a schematic representation of a second embodiment of a vibrating impact tool. This tool comprises a housing 42 having a central open ing therein which contains a solenoid 43. An armature of magnetic material 44 is positioned within the central opening in housing 42 so as to be free to move into solenoid 43 when the latter is energized. A spring 45 is positioned between the upper end of armature 44 and a cap 46 which is threaded to housing 42. Spring 45 vtends to retain armature'44 out of the center portion of solenoid 43. A suitable resilient means such as a; rubber pad 48 is positioned in the lower portion of the opening in housing 42 to absorb the impact of armature 44 striking housing 42. A spring can be used in this manner if desired. A rod 49 depends from armature 44, and a drill bit 50 is attached to the lower end of rod 49. Solenoid 43 can represent either a single solenoid or a pair of solenoids (such as shown in Figure 2) and can be energized by either of the electrical systems of Figures 3 and 4. The application of electrical energy to solenoid 43 results in armature `44 being lifted toward the center of the solenoid. This motion is resisted lby spring 45. The application of alternating current to solenoid 43 results in armature 44 and drill 50 being vibrated at the frequency of the current supplied. By applying two separate frequencies, the amplitude of vibration is modulated by the resulting beat frequency as previously de scribed in conjunction with Figure 3. This beat frequency periodically increases the amplitude of vibration. 'In Figure 6 there is shown a schematic representation of an impact tool employing a piezoelectric crystal. This tool comprises a housingSS having a central passage 56 therein. Piezoelectric crystal 57v is positioned within passage 56 and anchored at its midpoint to' housing 55 by supports 58 which yare formed of electrically insulating material. A rod 60 depends fromcrystal 57, and a drill lbit 61 is attached Vto the lower end of rod 60. First and secondelectrodes 634 and64 are mounted in spaced'relation with another on one side of crystal 57. Third and fourth electrodes 65 and 66 are mounted in spaced relation with one another on the second side `of crystal 57. Electrodes 63 and 64 can be yconnected to respective rst output terminals of generators 18 and 19 illustrated in Figure 3, and electrodes'S and 66 can be connectedto the respective second output terminals of these generators. Ifthe electrical system of Figure 4 is employed, then only a single electrode on each side of the crystal is necessary. The application of an altemating electrical eld of a frequency approximating the natural resonant frequency of the crystal results in the crystal being vibrated. This in `turn imparts vibrations to drill bit `61. The application'of two different frequencies results in a beat frequency which periodically increases the amplitude of vibration.

Figure 7 represents a modified form of the impact drilling tool of Figure 2. A hollow tube is threaded to housing 20 to form a conduit for the drilling iluid. A magnetostrictive sleeve 26 encloses etube 70 and is free t`o` slide thereon. Sleeve 26 is suspended from housing 20 by a heavy spring 71. A solenoid 23 encloses sleeve 26 and isv secured thereto by pins 72. Solenoid 23 is supplied with alternating current at one-half the mechanical resonance frequency of sleeve 26' and the drill bit assembly secured thereto. A second solenoid v is secured to housing 20', as by'pins 76'. Solenoid 7S is supplied with alternating current at a relatively low frequency to lift sleeve26"periodically. This periodic lifting of sleeve 26 serves todisengage the drill bit from the formation being drilled. Members 20' and 70`p`referably are formed of a non-magnetic material, such'as brass. Obviously, the assembly'of Figure 7 vcan employ a piezoelectric crystal in place of iragnetost'ric'tive` sleeve 26'.

From the foregoing description of several embodiments of the invention, it should be evident that there isy pro vided an improved `system of energizing electrically operated vibratory impact tools to produce maximumv vibrations. Two separate frequenciesv are applied to produce a resultant beat frequency `Vwhich periodically changes the amplitude of vibration so as todis'engage the drillebit from the member being"d'rille"d.` It'-l1'as"been found that this system greatly increases thel drilling speedff such a tool. vWhen the apparatusofethisfinverition is employed for such purposes as drilling `bore"holes iu 'the earth, a relatively large amount of power is' the alternatingv currents "are of frelativclyflowjfrequency. Such currents can advantageously be supplied by variable speed generators. When smaller tools are provided for purposes such as dentist drills, for example, the applied frequencies are considerably higher and can be supplied by electronic oscillators. It should be evident that the principles of this invention are applicable to any type of electrically energized vibratory tools and are not restricted to drills.

While the invention has been described lin conjunction with present preferred embodiments it should be evident that the invention is not limited thereto.

What is claimed is:

1. A drilling tool comprising an elongated member of a material having magnetostrictive properties, a first coil surrounding at least a portion of said member, the axis of said first coil extending longitudinally of said member, means applying an alternating voltage of a first frequency across said first coil, a second coil surrounding at least a portion of said member, the axis of said second coil extending longitudinally of said member, means simultaneously applying an alternating voltage of a second frequency across said second coil, and a drill bit secured to one end of said elongated member.

2. A drilling tool comprising an elongated member of a material having magnetostrictive properties, a coil surrounding at least a portion of said member, the axis of said coil extending longitudinally of said member, means simultaneously applying alternating voltages of first and second frequencies across said coil, and a drill bit secured to one end of said elongated member.

3. A drilling tool comprising a housing, a member of magnetostrictive material positioned within said housing, means attaching one portion of said member to said housing, a drill bit attached to one end of said member, said drill bit being positioned at least in part outside said housing, means carried by said housing to apply a magnetic field of first frequency to said member, and means carried by said housing to apply simultaneously a magnetic field of second frequency to said member.

4. A vibratory tool comprising a housing, a coil positioned within said housing, an armature of magnetic material positioned within said housing so as to move into said coil when current is passed through said coil, and means to apply alternating voltages of first and second different frequencies simultaneously to said coil.

5. A vibratory tool comprising a housing, a first coil positioned within said housing, a second coil positioned within said housing, the axes of said coils being coaxial, an armature of magnetic material positioned within said housing so as to move into said coils when current is supplied thereto, means applying an alternating voltage of a first frequency to said first coil, and means simultaneously applying an alternating voltage of a second different frequency to said second coil.

6. A drilling tool comprising a housing, a member of magnetostrictive material, resilient means suspending said member from said housing, a drill bit attached to said member, means secured to said member to apply a fluctuating magnetic field of first frequency to said member, and means carried by said housing to apply simultaneously a iiuctuating magnetic field of second frequency to said member to attract said member periodically.

7. A drilling tool comprising a housing, a member of magnetostrictive material, a spring suspending said member from said housing, a drill bit attached to said member, a coil enclosing said member to apply a fiuctuating magnetic eld of first frequency to said member, a solenoid carried by said housing to enclose a portion of said member, and means to apply simultaneously current of a second frequency to said solenoid.

8. A vibratory tool for permanently deforming a workpiece comprising a first source of liuctuating electrical energy of a first frequency; a second source of fiuctuating electrical energy of a second frequency; transducer means including a vibratory member, said transducer means being constructed and arranged for simultaneously receiving fluctuating electrical energy from said first and second sources and for converting the said received energy to vibratory movement of said member and deforming tool means connected to said member for delivering the vibratory movement thereof to the workpiece, thereby to permanently deform the workpiece.

9. The apparatus of claim 8 wherein said member has piezoelectric properties.

10. The apparatus of claim 8 wherein said member has piezoelectric properties; wherein said first frequency is a. first number of cycles per unit of time less than the resonant frequency of said member; wherein said second frequency is said first number of cycles greater than said resonant frequency; and wherein the vibratory movement has beat notes.

11. The apparatus of claim 8 wherein said member has piezoelectric properties; said transducer means includes first and second electrodes attached to opposite sides of said member and connected to said first source, and further includes third and fourth electrodes connected to opposite sides of said member and connected to said second source.

12. A vibratory tool for permanently deforming a workpiece comprising a transducer assembly which includes a first means that changes shape responsive to uctuating electrical energy applied to the transducer assembly; second means for applying fluctuating electrical energy of a first frequency to said transducer assembly; and third means for simultaneously applying fluctuating electrical energy of a second frequency to said transducer assembly and deforming tool means connected to said member for delivering the vibratory movement thereof to the workpiece, thereby to permanently deform the workpiece.

13. The apparatus of claim 12 wherein said first means comprises a piezoelectric member having a resonant frequency; said first frequency is a first number of cycles per unit time less than said resonant frequency; and said second frequency is said first number of cycles greater than said resonant frequency.

14. The apparatus of claim 12 wherein said first means includes means for connecting it to a drilling tool.

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